Controllers are used to provide control to the various components of an HVAC or refrigerant system, including one or more compressors incorporated in the system. Compressors are connected to the controller using one or more terminals that supply power to the compressor and control the operation of the compressor in order to operate the system. While a controller activates the compressors, it does not detect what type of compressor is present in the system.
Detection of the specific type of compressor allows the system to take advantage of special features of the compressor. For example, a system able to detect the presence of a multiple capacity reciprocating compressor allows the system to provide the appropriate control scheme to take advantage of the multiple capacities present in the compressor.
One known system used for sensing the presence of components in the system is disclosed in U.S. Pat. No. 6,089,310 (the '310 Patent). The '310 Patent is a thermostat for an HVAC system that includes a sensing transformer to confirm that a load has been applied to a preselected circuit. The sensing transformer is coupled to the load and generates a first indicator signal indicative of power being applied to the component. The thermostat controls the HVAC system by pulses to a latching relay to control a temperature load to an operating state selected by the thermostat. Current sensors indicate current flow through a particular temperature load, corresponding to an operating state. If the indication from the current sensors does not match the operating state selected by the thermostat, the process is repeated with a pulsing of the latch relays and comparison of the current sensors. Since the thermostat senses the load to the cooling or heating units, the thermostat is able to determine whether the heating or cooling unit has actually been turned on or off in response to a signal from the thermostat. However, the '310 Patent system has the drawback that it merely determines whether a system is on or off and does not determine what type or system or what type of compressor is present in the system. Further, the '310 system does not configure the controller to the type of system or compressor in response to the signal.
What is needed is a controller for an HVAC system that can automatically sense the type of compressor that is installed in the system and configures the controller output from the controller for the corresponding compressor attached to the system.